Apparatus for insulating coils



Nov.z s, 1932.

v. G. APPLE 1,887,005

APPARATUS FOR INSULATING C'OILS Filed April 19. 1929 lill PatentedNov. 8, 1932 UNITED STATES- VINCENT G. APPLE, OF DAYTON', OHIO` APPARATUS FOR INSULATING- COILS Application filed. April 19,

This invention relates to an improved method of insulating coils and has special reference to coils which are placed on, or about more 'or less complex structures of othermaterials.V

An object of the invention is to insure more and. better insulation between the individual turns of coils than has been possible by methods heretofore employed.

` A second object is to provide means and a procedure which will carry out the first object with minimum expenditure of labor and material.

Another object is to provide a' process and 5 apparatus whereby the more or less porous vcovering of ymagnet wire may be saturated and coated with an accurately determined layer of suitable insulating material in liquid form and partially `dried before it is wound into coils, to the end that there will be no excess of the liquid present which may get on the spool or core upon which the coil is placed, or on other surfaces of the structure, or in openings therein, where insulation would be'objectionable and where its removal would present almost insurmountable dilficulties after it became solid.

Another object is to employ insulating material of such a nature, and to soapply it between the turns of the coils aswill provide a structure wherein the winding is capable of withstanding great abuse and considerable distortion, lto the end that a layer of plastic insulation may safely bepressure molded thereabout, without injury thereto when-such a covering is deemed desirable.

That` these and many other objects and meritorious features of thel invention are at- 40 tainedvby the procedure hereinafter outlined and described, will be readily apparent to one skilled in the art from a consideration of the following description when taken in conjuncv tion with the drawing which illustrates a dynamo electric machine field lelement made according to the principles involved in my invention.

ln the drawing,

Fig. l shows apparatus for applying a coat- 5G ingof liquid insulation to a magnet wire 1929. Serial N0.'356,586.

which already has a covering of more or less porous insulation.

Fig. 2 shows apparatus for' winding the wire on a temporary spool where it may becoppe partially dry before it is wound into co1 s. l

Fig. 3 shows a set `of field coils wound from magnet wire treated by my process.

Fig. 4 shows six sets` of coils Fig. 3 in place in the field core, the core having secured thereto brush and line terminals to which the coil ends are joined.

Fig. 5 shows a mold within which the structure Fig. 4 is supported, there being sufficient vadditional space within the mold to receive a quantity of plastic insulation to form a cover or housing about the coils and terminals.

Similar numerals, refer to similar parts throughout the several views.

In the construction of wound electrical devices which are intended to withstand any considerable electrical pressure it is the usual practice to wind the s ools, or cores as the case may be, with con uctive wire having a covering of more or less porous insulation, usually a fibrous material such as cotton, silk, asbestos, etc. and subsequently to immerse the wound core in a liquid insulating material and then apply pressure to the container to 80 force the liquid to enter the porous covering of the wires and other interstices of the winding.

An vobjection to this method of insulating coils by impregnation is that often, after a coil is wound, and before it is impregnated with the liquid insulation, there are turns of the wire within the coil which are pressed so closely together, one turn against another, that the fibrous covering4 is almost, and some- 90 times quite, cut through, leaving adjacent turns in electrical contact, the condition occurring most frequently of course in a winding such as is employed on an armature, where many of the turns cross, one over the other.

0bviously, a sufficiently high pressure may force a liquid insulation to the innermost` turns of the wound coil, but there is no reason to believe that any amount of pressure on the container will force the liquid to enter and spread apart those turns which arealready in too intimate contact.

Another objection to the method of insiilating wound devicesby impregnation, is that would cover the binding posts and brush terminals, would enter the central bore which must afterward clear an armature, and would penetrate and lill the bolt holes which extend longitudinally through the core, and while tools may be made to exclude the insulation from these parts while impregnation is beingY effected, there is afterward substantially as great ditliculty in removing the surplus insulation from these tools as there would have been in removing it from the surfaces and holes of the wound element protected by them',

for it is a well known fact that some of the best known liquid insulating materials have also the greatest adhesive properties.

Because they overcome the foregoing and many other objections to theconventional method of insulating coils, the hereinafter described procedure is considered of great value in the art.

The coating apparatus Fig. 1 has a base' 10 upon which-is mounted a tubular body 11, divided near` itsmiddle into twoparts 12 yand 13, the parts being held together by a threaded sleeve 14. y

Body 11 is hollow, the space within being divided into two chambers 15 and 16 separated by a plug 17, which may be inserted and removed when the two parts 12 and 13 are separated by tlie removal of sleeve 14.

Plugs 18, heldin place by screw caps 19, close the outer ends of chambers 15 and 16.

Both plugs 18 as well as plug-17 have holes,

egtending longitudinally therethrough, of a diameter equal to that of the Wire to be coated.A

These plugs are preferably made from a material of a more or less yielding nature so as to permit the passage of a knot or a splice. Cork hasy split metal bushing imbedded at its center-is equally desirable.

A tank 20 extends from body part 12 and communicates with chamber 15. Upon re'- moval of filler plug 21 the tank may be partly filled with liquid insulation 22 as shown. An air-pump 23 has its discharge valve 24 con-v nected by pipe 25'to tank 2O and its suction I pended within, but does not touch chamber- 16. The endsl of coil 29 are brought out through insulating bushings 30 as shown. A second coil 31 is supported on metal brackets 32 extending from base 10. An electric current is made to ilow through coils 29 and 31 When'wire is being coated.

Magnet wire 33 comprising conductive wire covered with a thin layer of cotton or similar absorbent material is drawn from its spool 34 through one plug 18 into vacuum chamber 16 through coil 29 out of chamber lthrough plug 17 into the liquid insulation 22 in cham- `ber 15 and out through the other plug 18 and coil 31.

When the wire 33 enters chamber 16, the partial vacuum, together with the heat generated by resistance coil 29, takes whatever moisture there may be from the porous cover, sov that it enters chamber 15 dry, and with the pores of the fibrous covering under partial vacuum, and inasmuch as liquid 22 is under pressure it more readily penetrates all ofthe pores ofthe fibrous covering.

As the wire emerges from chamber 15 through plug 18 the surplus liquid is stripped off and retained in the chamber and the coating is given a definite size, depending of course Von the accuracy maintained in the opening through plug 18, As the wire passes through' heating coils 31, the liquid insulation is partly dried.

Whether the Wire is now wound on a spool suitable for keeping it in storage, or whether it is wound directly. on the cores or into n- `ished coils, depends somewhat on the nature ofthe winding.

Where an electrical device isr of such a nature as to require to be hand wound, or where the winding ismore or less tedious and apt to take wire more slowly than it comes from the coating apparatus, or where it is simple and takes wire more rapidly than it can be coated, l

it may be advantageous to wind the wire into a storage coil.

It will of course be understood that when the wire comes from the heating coil 31, the liquid insulation is not completely baked out, yet it is dried sufficiently to make the coating tough and somewhat pliable, and it will of course be still slightly sticky, so that, in order to successfully store it, `the reeling apparatus and theA storage coil which it yproduces are necessarily of special construction.

' The reeling apparatus Fig. 2 consists of a spindle 35 revolvable by pulley 36 in bearings 37 mounted on base 38. A worm 39 on the end of the spindle 35 drives wormwheel 40 whereby block 41 carrying wire guide 42 is recipiao noemen rooated through connecting rod 43. Worm 39 preferably has multiple threads of coarse pitch and wormwheel 40 is preferably of small diameter and ew teeth so that guide l2 may be reciprocated through a complete cycle in relatively itew turns orn spindle 35.

Because oi' this coarse pitch the wire is wound on the nose of the spindle with wide space between turns and the turns ot one layer crossing the turns of the layer beneath at considerable angle. Such a coil is commonly called a honey-comb coil, and is here wound in this shape, principally to prevent too great contact area and consequent adhesion between successive turns of a layer and between successive layers when the wire is unwound to be rewound into a permanent coil,

ig. 3 shows permanent coil i6 Iwound in three interconnected parts a7, i8 and 49 which adapts it to a slotted core 50, Fig., l, which l use lor the iield element herein selected lor illustration, the beginning 5l ot the inner section i7 being adapted to connect to one ci the line terminals, and the end 52 ot the outer section lil being adapted to connect to one ol the brush terminals.

ig. l shows the tield core 50 with sin. of 'the insulation treated coils i6 in place. lain-e terminals 53 and brush terminals 5l are insulated trom the core though secured thereto by screws which pass through insulation lined holes in the core. 'lhe proper coil ends are electrically' joined to terminals i3-and 54, as shown. rlhe structure comprising core 50, coils elo, line terminals 53 and brush terminals 5a may be designated as a whole by numeral 55.

rl"he structure 55 is now placed in a mold 56, Fig. 5, the essential parts ot' which are the outer body portion 5l having lateral pulls 58 which may be withdrawn from the completed molding to form brush pockets there in, the inner body portion 59 with the opening 60 passing therethrough and the plunger 6l snugly fitted to the opening 60. 'l he opening ii() may be called the stock chamber since it holds the loose molding compound 62 prior to the molding operation and the space 63 between body portions 57 and 59 may be called the molding chamber since the stock 62 is compressed into it.

lt will be seen that the stock chamber 60 shown with plunger 61 slightly entered, is in eect separate from the molding chamber 63, which is to form the finished housing, and that the end wall 64 of body portion 57 in etl'ect forms a bottom for the stock chamber 60, so that movement of moldable material from the stock chamber 60 into the molding chamber 63 must .be laterally of the movement of the plunger which forces the material out of the stock chamber into the molding chamber.

The reason for so constructing the mold and the manner of using it, is fully disclosed in my cro-pending application Serial No.

267,782 and consists briefly of placing the structure in the mold, heating the mold to a relatively high temperature, placing a measured quantity of the compound under the plunger 6l, putting pressure on the plunger to v:torce the unuxed compound against the upper surface 64 of body portion 57, maintaining the pressure until the compound absorbs sutlicient heat 'from the mold to become :duid and so tlow laterally from under the plunger into the molding chamber 63 and there be compressed hydraulically about the coils and to the contour ot the interior 63 of the molding chamber, then allowing the compound together with the insulation coating previously put about the individual turns of the coil to be hardened :trom the heat remaining in the mold.

Because oi the manner in which the molding pressure comes on the winding, that is, substantially equal in all directions thereon, very little distortion ol the coils results, and, because ot the manner in which the individual e winding are insulated, no ill effect results from such distortion ol the coils as may occun The advantages ol my improved method are numerous, lirst, the thickness of the insulat'on between turns of the coils is accurately controllable and does not depend on the space which may be lett between turns or which has been wound cotton or covered wire and afterward impregi ated a tluid insulation as in comtice; second, the liquid insulating mate;v is conserved, since it is ltept in tightly closed receptacle while it is being ap plied to the wire, instead of in an open tanlr where a considerable portion is always lost by evaporation and consequent adhesion to the tanl; and third, the liquid insulating material is not onlv placed where it will have the greatest eiifect but it is lrept on oit those portions where its presence would be objec? tionable, as on portions oi2 the core and terminals, and trom openings therein.

lWhile it has been heretofore proposed to so impregnato and harden a wound coil as to enable it to resist distortion when a layer of plastic insulation is afterward molded thereabout, the herein described process comprises new steps whereby I succeed in so insulating the turns of a coil, one from another, that the distortion which results when the further step of molding a casing of plastic insulation is afterward taken is withstood with no ill effect, and while the entire method consists of a plurality of steps taken in a given sequence, with tools having a number of novel features, it will be apparent that methods comprising less than the entire number of steps indicated, and apparatus having less than the entire number of features, may in many cases be employed and will produce a new and useful result, for

lll)

instance, on very small wire or Where the covering on the wire is very porous, or when the liquid insulation is very thin, keeping pressure on the liquid, or passing the wire through vacuum, may be dlspensed with, or when the wire is drawn through the coating apparatus very slowly the heating elements may be omitted, and while the preferred form of wound element comprises a jacket of plastic m insulation molded about the pre-insulated coils, the structure 55 may be heated so that the liquid insulation on the wire composing the coils will be baked, whereupon the structure may be mounted in a separately made housing of molded insulation or of other material.

Holding this view of the scope of the invention, I claim- 1. For impregnating the porous insulating covering on a conducting wire with liquid insulation, apparatus comprising, a receptacle divided into two closed chambers,I a. pump adapted to maintain vacuum in the first said chamber and pressure in the second said chamber, the second said chamber containing a supply of the said liquid, and means to draw the said wire through a snug fitting opening into the vacuum chamber, through a second snug fitting opening from the vacuum to the pressure chamber and through a third snug fitting opening from the pressure chamber.

2. Forimpregnating the porous insulating covering on a conducting wire with liquid insulation, apparatus comprising a receptacle divided into two chambers, a pump adapted to maintain vacuum in the first said chamber and pressure in the second said chamber, the second said chamber containing a sup- 40 plyr of` the said liquid, means to draw-the wire through a snug fitting opening into the vacuum chamber, through a second snug fitting opening from the vacuum to the pressure chamber and through a third snug fitting opening from the pressure chamber, a heating element within the vacuum chamber adapted to surround and heat the wire as it passes therethrough, and a second heating element placed so as to surround and heat the wire as it emerges from the pressure chamber. h Ir testimony whereof, I hereunto set my VINCENT G. APPLE. 

